Clock setting system



Feb. 21, 1950 Filed Aug. 29, 1942 L. J. STERN CLOCK SETTING SYSTEM 3 Sheets-Sheet 1 '75 5 M W E, fIELI n 5 IE.

' @12 IE 12. lg IE1 LEWIS J. 5 Team ZAQ Feb. 21, 1950 L. J. STERN 2,498,462

CLOCK SETTING SYSTEM Filed Aug. 29, 1942 3 Sheets-She'b 2 FIELE LEWIE .ljTElKN.

Feb. 21, 1950 L. J. STERN 2,498,462

CLOCK SETTING SYSTEM Filed Aug. 29, 1942 3 Sheets-Sheet 3 Patented Feb. 21, 1950 CLOCK SETTING SYSTEM Lewis J. Stern, Adrian, Mich, assignor, by mesne assignments, to Sperti Faraday Inc., a corporation of Ohio Application August 29, 1942, Serial No. 455,718

2 Claims. 1

This invention relates to a system of independently operable devices and a monitor device therefor.

This invention has utility when incorporated in synchronous m'otor operated electric time pieces for master clock periodic resetting of the time pieces as secondary clocks in a system.

Referring to the drawings:

Fig. 1 is a perspective view of a housing or container for clock resetting and control of secondary clocks from a master clock;

Fig. 2 is a view, partly in medial section of a secondary clock speed-up mechanism and controls therewith;

Fig. 3 is a fragmentary view of the master clock switch as a control for the secondary clock speed-up mechanism of Fig. 2;

Fig. 4 is a plan view of the switch controlling arm or lever of Fig. 3;

Fig. 5 is a view of a secondary clock face and mechanism of control therein;

Fig. 6 is a plan view of the lever or control device of Fig. 5 in position at the solenoid;

Fig. 7 is a view of portions of the device of Fig. 5 at the hold or stop position for the secondary clock;

Fig. 8 is a view of the device of the lever cam, and solenoid from the left of Fig. '7; and

Fig. 9 is a. wiring diagram of the general system as interconnected from a master clock to secondary clocks.

THE GENERAL STRUCTURE The special cooperating features herein involve the switch at the master clock (Fig. 3) the control features at the secondary clocks (Figs. 2 5), and the electric inter-relating control therefor in the housing (Fig. 1). Upon a base 1, screws 2 may assemble a cover or housing 3, having a handle 4. 110 volt, 60. cycle electric current may be fed into the housing 3. by supply lines 5, 6. A switch 1 may cut in the current from the lines 5, 6. Manual resetting, say for the electric clocks after an. interval of power failure, may be effected from positioning a switch 8.

From the housing 3, electric lines 9, l0, extend to a synchronous motor of a. master clock; ll. Additionally, control lines I2, 12, are in a conduit [3 with the lines 9. Ill, from the housing 3 to the master clock. The box or housing 3 is a sort of central station of control with a conduit l4 having branches [5 extending to the various secondary clocks it of the system. Conductor lines ll, l8, in the conduit l4 provide the power current for synchronous motors at, the respective 2 secondary clocks. A third control line I9 is also in the conduit [4.

THE CONTROL FROM THE MASTER CLOCK MINUTE HAND 'ro PICK UP SECONDARY CLOCK LAGGING MINUTE Ewes For controlling the several clocks with a minimum of discrepancy between the time indications thereof, applicant has herein developed the control for recurring at intervals of one hour. Applicants experience has been the portion of the hour where clock time changing may be least open for question is 34 minutes after the hour. which time feature of control is adopted at the master clock II.

The master clock minute hand operating wheel 29' (Fig. 3) has projecting laterally therefrom 2. lug ll located to ride against a cam lug 22 projecting upward from the edge of a lever 23. The lever 23 has a fixed fulcrum 24. A tension helical sp-rirr 25 pulls the lever 23 upward in the path of the lug 2 l'. The lever 23 is thus yielclably held in the path of the lug 2 l of the minute hand operating wheel 20 of the master clock I I. When the lug 2| rides along the lever 23 to the cam lug 22 thereon, the lever 23 is rocked on its fulcrum to shift downwardly offset free end 26 and move a switch contact 21 to abut a companion contact 28. This closing of the switch 21, 23, is for but a brief interval during the continued rotation of the wheel 2f However, this interval is effective thru conductor lines l2, l2 as extending from the clock I l hack to the housing or box 3.

This control connection from the master clock ll back to the housing 3, in its transmission therethru goes to. the control line IQ for the respective secondary clocks [6. In each of these secondary clocks it, there is a solenoid 29 (Fig.

The circuit by way of the line I9, is completed by lines ll, 6. With the solenoid 29 thus energized, a core 30 therein is axially shifted against the resistance of compression helical spring 35. This movement of the core 30 takes with it a brass or non-magnetic sleeve 32 therein which fixedly mounted thereon a gear, wheel 33. Accordingly, in this shifting of the core 30, and sleeve the gear 33 is pulled away from a Bakelite friction, clutch face 34, toward which it had been held by the spring 3 I. From the opposite sideof the gear 33 to that as toward the clutch face the gear 33 has a rubber-like or neoprene friction clutch face 35. The unclutching of the gear from the face 34 has now effected a clutching at the face 35 with the face of a The gear 35 is coaxial with the, gear 33 and is loose in a hearing 31 about the sleeve 32.

In the sleeve 32 is a mounting shaft 38 therefor, which not only locates the spring 3|, but is mounted to extend against clock housing plate 39 and thru clock housing plate 40.

The secondary clock synchronous motor 53 perates a driving pinion 4| (Fig. 2) in mesh with a gear 42 with which the axially shiftable gear 33 is in mesh to be driven thereby. When this gear 33 is in its normal position, that is, against the clutch face 34, it serves to drive a pinion 43 in mesh with a gear 44 fixed with a pinion 45 on a shaft 46. The pinion 45 is in mesh with a gear 41 on a minute hand shaft 48.

Therefore, it is to be noted, that the energizing of the solenoid 29, by disconnecting the clutch 34, renders ineffective the drive thru the ears 43, 44, 45, to the gear 47. However, there is simultaneously a reconnection, for the transmission from the gear 33 to the gear 36 for speedup driving of a pinion 49 fixed on the shaft 46. The speed reduction train 43, 44, is now in reverse but as disconnected from the gear 33, it means nothing. By selecting neoprene for the clutch face 35, it is desired to have such face not subject to deterioration if it be exposed to oil.

The high speed driving from the gear 35 is something which occurs or it is intended to have taken place only when the particular secondary clock be behind time. A secondary clock minute hand 50 which is lagging is, by this connection, speeded up in the minute from 34 minutes after the hour to 35 minutes after the hour.

FORWARD LIMIT SET AND RELEASE FOR THE SECONDARY CLOCK MINUTE HANDS The discussion as just had has to do with the lagging or too slow secondary clocks, and the cure therefor. When the secondary clock has been running too fast, or overrunning, another control for holding back is herein effective. To this end, the gear 41 (Figs. 2, has a lug 5|. As the secondary clock l3 has its minute hand 50 come to the 35 minute past the hour position, the lug 5| moves against a projection 52 on a lever 53. A tension helical spring 54, in pulling the lever 53 upward into the path of the lug 5|, shifts the lever 53 longitudinally for a slot 55 to ride on fulcrum pin 55. Accordingly, when the lug 5| strikes the hump or projection 52, it

shifts the lever 53 lengthwise, to move the fulcrum pin 56 from the end of the slot 55 toward the projection 52, away therefrom and toward the fulcrum end of the lever 53.

' Accordingly, when the gear 41 on the minute hand shaft 48 is driven, either thru the train 43, 44, 45, or the train 35, 49, 45, and the lug 5| comes into service at 35 minutes past the hour time for the secondary clock I5, the lever 53 is shifted lengthwise and offset cam free end 51 thereof is brought into position at the side of a disk 58 mounted on a plunger or core stem 59 of a solenoid 30. The location is thus given the end 5'! of the lever 53 between the disk 53 and the solenoid 30. It follows then, as the solenoid is energized, the disk 58 is moved to carry with. it the free end of the lever 53, thereby to move the lever 53 sufliciently to be clear of the lug 5|. As thus released, the spring 54, at once resets the lever 53 and its projection 52 for the next cycle operation.

The interval of operation which releases the clutch 34 and connects the clutch 35 is one minute from 34 minutes past the hour at the master clock ||,.to 35 minutes past the hour. This electric circuit control is thru the lines IT, IS,

as to the secondary clocks, and is at a different voltage for response thru the coil 29, than is required for the coil 50. From the housing 3, a differing or higher voltage control comes in at the 35 minute period past the hour at the master clock for the secondary clock control. This higher, voltage, as energizing the coil or solenoid 60, snaps the lever 53 clear of the lug or stop 5|, thereby releasing the wheel 47. The minute interval for the clutch 35 having been completed at this time, the clutch 34 at once picks up thru the gear train 43, 44, 45, for the normal driving of the minute hand shaft mounted gear 41 until the next resetting control period be reached at 34 minutes past the next hour.

WIRING LAYOUT Control motor cut in and out out The housing 3 has therein an assembly of electrical devices inter-actin in response to the master clock control lines I2, l2, in transmitting the control to the secondary clocks |6 as responding thru the lines |9, ll, 3.

The power supply line 5, upon the closing of the switch I, is connected thru a line 5| with the lines Ill, 6| to the switch contact 21 at the master clock synchronous motor For a brief interval in the rotation of the minute hand wheel 20 of the master clock II, the lug 2i (Fig. 3), throws the lever 23 to close the switch 21, 28.

From the closed switch 28, there is the line |2 to a relay coil 63, with a line 64 therefrom to a switch contact 65. Besides various coils, there is in the housing 3 a motor 14 and a set of cams '|88| as timing controls actuated from the motor. The contact 65 is in this timin control system at complementary switch contact 55, at this interval closed, so that current flow circuit may be completed from the contact 56 by a line 61 to the power supply line 5. There is but one coil in this circuit, the coil 63, which is now energized. The energized coil ,63 now closes a normally open switch 68 which has connection thru a line 69 with the line one way, and the other way with a contact 10, in the line l2 to the coil 53. It is thus seen that the switch 58, I0, is in parallel with the switch 21, 28. Therefrom it follows, that notwithstanding the switch 21, 28, be closed for operation but for a brief interval, in so doing, it has brought in the switch 68, 10, to hold the coil 63 energized.

In addition to the switch 68, T9, the energized coil 63, closes a switch H, 12, thus connecting the line 59 from the line ill, with a line 13 to one side of a motor T4. The other side of the motor '54 is connected by a line with the line 6. The coil 53 has thus functioned not only for holding in itself from the quick cut in and out operation of the switch 21, 23, but has started the control motor 14.

The motor 14 has a speed reduction transmission 16 therefrom to a shaft H on which are located a series of cams. The working cycle is for the motor 14 to rotate the shaft one complete turn. The shaft Tl hasfixed thereon cams 13,19,80,8|.

In order to maintain actuating current for the motor 74 for the full rotation cycle of the shaft 11, an additional or supplemental power supply connection is provided in parallel with the switch 12. This additional connection is thru a line 82 from the line '13, to a switch contact 83. A cam 84 on the disk l8, once the motor 14 starts, rides away from a spring arm 83. This 75 then-allows the contact 83' to close with a switch 11., 12, should be opened after the motor 14 has started, the power current for the motor 14 will be maintained until the cam lug 84 makes its complete rotation back to ride under the spring 86 and move the contact 83 clear of the contact 85. The switch 86, 85, is thus opened, breaking the power circuit to the motor 14 at the completion of one full rotation of the cam shaft 11.

The switches H, 12, and 68, 10, at the relay or coil 63 are normally open. However, at the energizing of the coil 63, they are each closed at the same time. Connected to the power line 13 to one side of the motor 14 is acoil 88 with line circuit completing connectiontherefrom to theline 6. The coil 08 is thus in parallel with the motor 14; Similar to the solenoid 29in the secondary clocks I6, there is a solenoid coil 9| in the master clock I I having line connection 92 with the line 9 to the motor H. From the coil III a line I2 extends to a contact 89, normally closed and adjacent the coil 88. With switch 89, 93, closed, there is circuit thru a line 94 to the switch 8, which is normally open. Theswitch 8 is closed as a manual control for speed-up setting of the master clock II. For this circuit, there is from the switch 8, a line 95110 a rectifier 96, say as the positive side, with a negative line IOI: from the rectifier 96 to a choke coil I02, and by a line I03 to the lines 6, 9, in completing the direct current circuit for the coil 9I. The coils 9 I, '29, are low voltage, say 12 volts, and from the transformer 98, the energizing circuit therefor is. from the lines 91, I01, the latter being a mid-transformer take-off or tap, line. Considering the positive wave half from the line 91 to the rectifier 96, its circuit is by the linev 95, closed switch 8, line 94, closed switch 93., 89, line I2 to the coil 9|, and, from thence by the'lines 92, 6, 6, I93, choke coil I02, line IN, to the. rectifier 96. The energizing circuit therefor to the transformer 98 by the line I01 is thru switch H6, H5, closed by the starting of the motor 14. moving the disk 8! to have the arm II8 ride out of the short radius portion H9. The circuit to the switch H5 is by the line 2 I from the rectifier 98. The next half wave positive current from the transformer 98, instead of by the line 91, is now by the line I01 thru this last-traced circuit to the rectifier 96 by the line II 4. The direct current thus is from the rectifier by the line 95.. and the herein-v before traced circuit back by the line IOI, while the energizing circuit therefor by the line II-4 passes back to the transformer 98 by the line 91.

Simultaneous manual setting of the master and secondary clocks The manual setting of the master clock II is achieved by the operator observing the clock II when the switch 8 is closed, and opening the switch 8 as the energized coil 9! has thru a clutch 35 with a wheel 36 operated the minute hand operating wheel 80 of the master clock, to bring the minute hand of the clock up to the desired clock setting position. The occasion for this manual control is at starting initially, or to correct the system after an out-of-service interval, as from lack of electric power supply. The energizing of the coil 88, which is effected at all times that the motor 14 is running, opens the switch 89, 93, and thus provides a positive safeguard against any manual disturbance during the. automatic functioning of the contnql in the 1 menes housing 3. With the switch 89, 93, open there is not a power supply to permit an energizing of the coil 9| in the master clock II. Therefrom it follows that the driving clutch 34 from the motor II is continuously in driving relation for operating the minute hand operating wheel 20. In this manual resetting, the coils 9!, 29, are in parallel, which means that the direct current in energizing the coils 29 at the secondary clocks I6, brings about a resetting of the entire system as the master clock I I is set.

Low voltage connections for the coils 29, 91

These clock setting speed-up drive coils 29, 9|, are low voltage. The control therefor is coincident or in parallel, for at the coil 88, besides the normally closed switch 89, 93, is a switch [04, [05. One way from the switch I04, I05, is a line I06, which as the switch 8 be manually closed, is connected with a line I01 to a mid or intermediate take-off connection with a transformer 98. The transformer 98 has a line connection 99 to the power line 6 and another line connection I00 to the power line I0.

The other way from the switch I04, I05, a line I08 extends to a line H4 and the rectifier 96, which has its other side connected by a line 91 with the transformer 98. The direct or continuous current is from the positive side of the rectifier 96 thru the lines 95, I9, to the coils 29, 9|, and from thence by the lines I1, 6, I03, thru the choke coil I02 and the line I0! to the rectifier 96. The energizing current for this circuit is from positive half waves coming alternately from the lines 91, I01, the transformer 98 to the rectifier 96, for the low voltage coils 29.

High voltage connection for the coil 60 A lug I I2 on the cam disk 80, just prior to completing the counterclockwise single rotation cycle (Fig. 9), rides against a, spring arm I I3, first to open the switch 66, 65. This de-energizes the coil 63 for simultaneously opening the switches 1|, 12, and 68, 10. The lug 84 on the cam disk 18 is at this time still away from opening the switch 83, 8,5, and accordingly the motor 14 remains running. During this short interval of continued running of the motor 14 until the switch 83, 85, be opened, the opening of the switch 65, 66,, by the lug II2 on the cam disk has connected a switch contact I09 from the line I08, with aswitch contact II 0 to a line III to a higher voltage connection relation with the transformer 98 than the connection I01.

During the cycle interval of the lug 84 on the cam disk 18 and the lug I I2 on the cam disk 80, the cam disk 8I has its short radius portion II9 exposed to have a spring arm IIB ride therein, thereby to. leave during this period a switch II 5, I I6, open. At the starting of the operation cycle, as the arm II8 rides out of the reduced diameter portion I I.9, the switch I I5, H6, is closed to connect mid transformer line or low voltage. connection I01 with a line II1, thru the switch H6, H5 and the line I I I in completing transformer energizing circuit, to the rectifier 96. This closing of the switch IIB, H5, is for a circuit in parallel with the switches I04, I05, and 8 providing an additional circuit for energizing the rectifier 96 from the transformer 98, in which additional circuit these switches I04, I05, 8, are in series. The iunctioning; of the cam 80 to have its lug II2 close momentarily. the switch I09, I10, for the rese ti n om he an m r by the line I II, to pass'by the line IM tothe rectiher 96, takes place as the switch I I5, I I6, is opened at the cam disk 8I, during the automatic control program sequence of the supplemental circuits.

The higher voltage, say 24 volts, for the coil 60, as against 12 'volts for the coils 29, SI, energizes the coils 60 for shifting the levers 53 clear of the lugs The secondary clocks I6 are thus released for normal running.

The choice coil As disclosed herein, the electric clocks II, I6 are power actuated from an alternating current electric circuit. The control elements as of alternating current are completed thru the power supply lines 5, 6. However, the direct current circuits as, developed herein, are complete in the wiring diagram showing of Fig. 9. Alternating current cycles or pulsations from the lines 6, I03, on one side, and from the line 5, closed switch I, the line iii, the switch I23, the line I8, the motor t6, the line H, the coils 29, 65, the lines I9, 95, the rectifier 9t, and the line I6! on the other side are not passed by the coil I02. Furthermore, from the choke coil I92, there is shown direct current line I93, to the line 6 for the several coils 9|, 29, Eli, from which the circuit as direct is completed by the lines I2, 92, I9, 95. It follows that the direct current control coils 9|, 29, 60, do not have their performance disturbed by alternating current.

Secondary clocks transition from resetting As the interval for the direct current high voltage is about to pass from causing the secondary clock levers 53 to clear the stops SI for the minute hand wheels 41, there is not accumulated force to put the wheel 41 in motion from the action of the spring SI having thrust the clutch 33, 34, into transmission relation. The cam disk I9, just before the completion of the control cycle for the shaft 11, has its recess I2I in position for a spring arm I26 to drop thcreinto. Thereupon, the switch I22, I23, is opened, and the 110 Volt current from the line BI to the line I8 is interrupted.

The motors I5 of the secondary clocks are thus cut out. Immediately thereafter, the arm I20 rides out of the recess I 2| at the cycle completion for the shaft TI. The switch I22, I23, is closed.

The secondary clocks I6 having thus been precleared of torque disturbance, are now started simultaneously at the reset position dominated and carried thru by the automatic control.

Adaptation to different clock systems In the event of current failure to the system, a stand-by master clock, operated from a source of stored energy, measures the period of the current outage, whereby on resumption of power to the system, the contacts I25, I26, may be closed to reset the system. This stand-by master clock may be housed in a unit I24, including a synchronous motor device I21 for controlling the operation of the stand-by master clock during normal operation of the system.

The automatic control operation Regardless of whether the master clock I I, I27, or I26, be in control, under the particular program for hourly corrections, the lugs 5|, at any of thetoo-fast operating secondary clocks l6, come into action at 35 minutes past the hour. Thereby each of these too-fast secondary clocks is stopped for the interval until the hourly incoming minute of the automatic control be completed. the

automatic control nears the end of the 34 minute cut-in and is about to reach the 35 minute point, the coils 60 are energized. The respective secondary clock hold back levers 53 are kicked clear of the lugs 5i. All of the secondary clocks I6 in the system are thus simultaneously released to start the succeeding hour, each as set at 35 minutes past the hour.

The too-slow or lagging secondary clocks, each receive control attention commencing at 34 minutes past the hour. The precision of this timing cut-in is from the master clock switch 21, 28. Inasmuch as the master clock operation continuity is not checked, the closing of the switch 21, 28, is of short duration, that is, less than to 35 minutes past the hour, in which one minute the control is to function. The closing of the switch 21, 28, in energizing the coil 63, has such coil maintained energized, by closing the switch 68, ID, in parallel with the switch 21, 28. Accordingly, as the switch 21, 23, is opened, the coil 63 is kept energized.

The energizing of the coil 53, besides closin the normally open switch 68, It, also closes the normally open switch 1!, E2, in circuit to start the motor l5. Upon this starting of the motor l t. the cam disk I8, cuts in the switch 83, 85, for a circuit in parallel to the switch II, I2. This provides a hold-over to just short of completing the full rotation of the shaft 17, for the motor '14, so that the coil 63 may, in the interval before the lug 6d opens the circuit for the motor I4 to stop, be de-energized by the lug H2 opening the switch 65, 66.

As the shaft ii starts its counterclockwise rotation (Fig. 9), the cam disk 8i closes the switch I I6, I I5, and thereby connects the transformer 98 into low voltage supply to the rectifier to energize the secondary clock direct current coils 29. Lines ll, 6, from the coils 29, connect by line I63 to the choke coil I92 in completing the direct current circuit to the rectifier 95 by the line It i The energizing of the coils 29, overcomes the springs 3| to disconnect the gears 33 from the clutch faces 34. This cuts out the normal speed reduction drive to the minute hand wheels ll. Simultaneously the shifting of the gear 33 away from the clutch face 35, connects the clutch face 35 with the gear 36, for a high speed driving of the minute hand wheel 41. This driving of the wheel 41 can only proceed until the lug 5| catches the lever 53. It is thus seen that any retained connection for the face 35 means slippage as to the wheel 35, until the coil 29 be de-energized. Inasmuch as the too-fast clocks have been stopped by the lugs 5|, there is this non-detrimental slippage thruout the system at the secondary clocks as brought to the correct reset position.

The reduced diameter portion H9 at the cam disk 8|, allows the switch H5, H5, to open, deenergizing the coils 29. Immediately, the lug H2 closes the switch I99, lit, for a higher voltage connection to the transformer 98 to be effective thru the rectifier 95 for energizing the coils 66. Thruout, the levers 53 are tripped clear of the lugs 5!. The shaft l7 rotation is then completed. The control is cut out. The clock system is back in service to run until 34 minutes past the next hour.

What is claimed and it is desired to secure by Letters Patent is:

1. A clock system comprising a plurality of electric motor driven secondary clocks, a transmission in each of said clocks including a normal 7 5 driving clutch and a high speed clutch, a shiftable member directly in the transmission between the clock motor and each of said clutches, time indicating means for the respective clocks, said clutches being between the motor and the time indicating means therefor, stop means for the time indicating means between the time indicating means and the normal driving clutch effective as the time indicating means reaches a predetermined position, a master clock having a switch, means in the master clock for actuating said switch at an interval in advance of the predetermined time position for the secondary clocks, circuit means for energizing the respective clocks for the normal operation thereof, in addition to said circuit means an additional electrical circuit means from the master clock switch to the secondary clocks, an electric release means for the stop means, a difierent electric control means for shifting the normal driving clutch, said release means and control means being energized by said additional electric circuit means, and transmission modifying means actuatable from the master clock switch through the additional electrical circuit means in conjunction with a portion of said circuit means to shift said member for disengaging the normal driving clutch from being driven through the member from the clock motor, to cause the member to connect the clock motor through the member to operate the high speed clutch to bring the secondary clock time indicating means to said predetermined position.

2. A clock system comprising a plurality of electric motor driven secondary clocks, a transmission in each of said clocks including two-way clutch shiftable member directly in said transmission and operable from the clock motor, said transmission one way from the member embodying a normal driving clutch and the other way from the member embodying a high speed clutch, time indicating means for the respective clocks, said clutches being between the motor and the time indicating means therefor, stop means for the time indicating means between the time indicating means and the normal driving clutch efiective as the time indicating means reaches a predetermined position, a master clock having 10 a switch, means in the master clock for actuating said switch at an interval in advance of the predetermined time position for the secondary clocks, circuit means for energizing the respective clocks for the normal operation thereof, in addition to said circuit means an additional electrical circuit means from the master clock switch to the secondary clocks, an electric release means for the stop means including a solenoid, a. different electric control means including another solenoid for shifting the normal driving clutch, said release means and control means solenoids being energized by said additional electrical circuit means, and transmission modifying means actuatable from the master clock switch through the additional electrical circuit means in conjunction with a portion of said circuit means and the shiftable member for disengaging the normal driving clutch from being driven through the member from the clock motor, to cause the member to connect the clock motor through the member to operate the high speed clutch to bring the secondary clock time indicating means to said predetermined position LEWIS J. STERN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,622,588 Hoxie Mar. 29, 1927 1,822,144 Harter Sept. 8, 1931 1,887,221 Thomas Nov. 8, 1932 2,026,368 Warren Dec. 31, 1935 2,101,432 Harrison Dec. 7, 1937 2,120,353 Faller June 14, 1938 2,167,829 Faller Aug. 1, 1939 2,248,164 Dicke July 8, 1941 2,289,636 Engel July 14, 1942 FOREIGN PATENTS Number Country Date 790,914 France Sept. 16, 1935 

